1. Field of the Invention
The present invention relates to a light-polarizing sheet for liquid crystal display devices.
2. Description of the Prior Art
The conventional liquid crystal display panels are made from a light-polarizing sheet laminated on a base glass plate with an adhesive agent. The manufacturing procedure is illustrated in FIG. 1. (A) a conductive layer (2) is formed on one side of a base glass plate (1), (B) a literal pattern (3) is formed by such an appropriate procedure as photo-etching or printing, (C) the surface is covered with an oriented film (4) by coating and thus coated layer is rubbed and seal-printed. (D) two conductive base plates (5) thus obtained are brought together with a spacer (6) and the space or clearance is saturated with a liquid crystal (7). On the other hand, (E) a light-polarizing sheet (13) is prepared from a light-polarizing element film (8) laminated with a supporting film (10) with or without an adhesive (9). And the one surface of the supporting film (10) is bonded with a release film (12) with a pressure sensitive adhesive (11). (F) another light-polarizing sheet laminated with a reflexive plate (14) on one surface is prepared by the same procedure. (G) each of the light-polarizing sheet (13) is bonded on the back side of the base conductive plate (5) [of the base glass plate (1)] with a pressure sensitive adhesive after peeling off the release film (12).
However, the reduction of the thickness of these panels is impossible, because the mechanical properties of the base glass plate are limited. These composition prevents a continuous procedure (endless length of film) that is expected from an efficient production. Moreover the poor impact strength is a problem and panels made of a plastic film (or sheet) are looked forward to.
Plastic sheets, however, have the following problems for this object.
(1) have tendency to deteriorate when it is exposed to organic chemicals during pattern-forming processes and to liquid crystals during the saturation process.
(2) poor moisture resistance
(3) insufficient flexibility, and even insufficient rigidity to give good workability for panel assembly.
(4) thickness reduction may be realized but have such problems as distortion and bending of panels and heterogeneous clearance.
(5) may form bubbles by heating, because some pressure sensitive adhesives that have tendency to give bubbles by heating are used for lamination.
(6) insufficient dimensional stability at an elevated temperature.